1. Field of the Invention
The present invention relates to hydraulic powered wrenches particularly those used on ships which drill for oil.
2. Description of the Prior Art
Any table of element quantities can be referred to to prove that the total amount of hydrocarbons in the lithosphere of the earth is more than one billion times as much as the human race uses annually. The hydrocarbons come in three main types, high molecular weight which are gases such as natural gas, although the gases may be dissolved, and intermediate weight molecules which comprise petroleum, also referred to herein as oil. While the total amount of hydrocarbons is enormous, it is economic at present only to remove those which can be removed least expensively. Various natural processes have consentrated petroleum in various pressurized and not pressurized volumes. Oil drilling comprises drilling a hole down to a volume where the oil exists either pressurized so that it comes up without pumping or less pressurized so that pumping is necessary to bring the oil to the surface.
Economically, it makes sense to drill for the oil which is cheapest to bring to the surface first then leave the balance of the oil until later when a shortage has driven up the price or when technology has advanced sufficiently so that the cost is no longer as high. For this reason, the land surface of the United States has been drilled a substantial number of times and it is believed that substantially all of the larger concentrations have been tapped. After the larger concentrations in convenient locations are tapped, the oil industry has two alternatives, it can tap lesser concentrations in convenient locations or greater concentrations in less convenient locations. It does both.
The U.S. Geological Survey has estimated that more than 100 billion tons of oil will eventually be burned beneath the U.S. continental shelf. Oil drilling ships and platforms have been designed and have been in operation for years to attempt to tap this vast potential source of petroleum. The cost of operation of ships may exceed $100,000 a day and the cost of oil drilling platforms is also high. Accordingly, any down time, even of a few minutes, may cost thousands of dollars. Because of this, even a small improvement in the operation of the oil drilling ships is economically worthwhile, even though cost may appear to be very high for only a slight improvement.
When one is drilling perhaps more than a mile beneath the surface, some of the equipment at the surface is relatively large. Bolts, for example, may be very large and tightened under pressures far beyond hand strength. For this reason, hydraulic wrenches are utilitzed to tighten and loosen bolts and other similar assemblies. Hydraulic fluid under pressure is available on these ships, and the prior art as well as the present invention makes use of this hydraulic fluid to drive hydraulic wrenches.
The prior art hydraulic wrenches use two radial ratchets one right hand and one left hand, which alternatively drive a square standard socket drive. These wrenches must be disassembled and reassembled with additional parts weighing 10 to 15 pounds to change directions. What is needed but not found in the prior art is a hydraulic wrench which cannot break without the use of these special tools which the prior art uses for installation or removal in order to change direction of the wrench. In addition, with the prior art, there is the problem of making and stocking hundreds of sizes of retaining rings which rings are used on prior art hydraulic wrenches. The prior art has a requirement for access to the end of the end of the hole. This in turn makes necessary a requirement that the groove be relatively close to the end. The present invention eliminates this requirement since it utilizes a coiled retaining ring which is installed tangent to the shaft and may be located at any point along its length. The prior art includes a problem of holding a shaft and preventing it from moving axially in either direction. The present invention overcomes this difficulty by locating the part of the annular groove in the hole and part on the shaft. An installed coiled retaining then transgresses the shaft/hole interface and holds both parts relative to each other.
Prior art problems solved by a wrench according to the present design, not counting the retaining ring, include the avoiding of transverse loads and the consequential moments which are avoided by positioning the reaction arm in a wrench according to the present invention in the plane of the fastener drive head. A splined sleeve transmits torque of the drive arm to the driven cylinder.
This assembly-reassembly is avoided by providing only one single radial ratchet to drive a socket which has two surfaces mating with a bolt, so that disassembly and reassembly is not necessary, to change directions one merely uses the other surface of the socket. In addition, minor problems are cured such as the problem of not being able to locate the power supply and control valving in close proximities to the wrench which problem is avoided in the present invention by placing at least one control valve on the torque wrench assembly, for use by the wrench operator, and utilizing a cylinder which is large enough so that hydraulic power already widely distributed on a drilling ship or platform can be used directly to provide the force needed to torque the wrench. This capability of utilizing lower pressure also means that parts do not wear out as quickly as on the higher pressure prior art wrenches.